Get experience working along side an experienced inspector. You have no excuse, just because you once worked with a poor electrician that doesn't mean that you can go throwing yourself head first into jobs that you don't know how do do.
Here's some helpful advice for you; learn how to walk before you start running.
It's not abuse fella, it's the hard truth. In terms of inspection and testing knowledge, mine is already far superior to yours, therefore I don't feel the need to do anything to make myself 'feel' superior. That superior knowledge gives me the ability, and the right, to say that you currently don't posses the level of knowledge needed to be carrying out inspection and testing work if you have to be asking such basic questions. You can't just take the work on and expect people on forums to answer questions, that you, as an electrician who has taken money in exchange for testing and inspection services, should know!
Finally, as you asked, I have time to spend on here in between emailing invoices to my many customers, customers whom I have gained over many years who give me money to carry out work that I can actually do, and do bloody well!